Electrically variable complex slot



July 19, 1960 H. E. sHANKs ELECTRICALLY VARIABLE COMPLEX snow Filed June 18, 195e 2,946,056 Patented July 19, 1960' 2,946,056 v ELECTRICALLY VARIABLE COMPLEX SLOT Howard E. Shanks, South Pasadena, Calif., assgnor to Hughes Aircraft Company, Culver City, Calif., a corporation of Delaware Filed June 18, 1958, Ser. No. 742,804

9 Claims. (Cl. 343-768) The present invention relates to a variable conductance waveguide slot and more particularly to an electrically variable complex slot.

A mechanically variable complex slot is described in an application for Letters Patent, Serial No. 742,805 filed lune 18, 1958 by the applicant of the present application, and reference is made to such copending application for a general discussion of variable conductance waveguide slots.

In brief, resonant slots through the broad wall of a rectangular waveguide along the centerline thereof do not radiate; however, the current distribution of energy propagated by the waveguide can be asymmetrically disturbed to provide a component of current transverse to the slot so that radiation occurs. The amplitude of radiation is controlled by the value of the component of current that is transverse to the slot whereas the phase of radiation is controlled by the direction with which the transverse current component crosses the slot.

In the above referenced patent application, rectangular waveguide slots -of a broad wall are made to radiate with desired variations in amplitude and phase by mechanically altering the transverse position of two irises associated with the slot. While this procedure has advantages over previously known slot radiators for numerous uses, the mechanical movement is inherently slow acting and subject to wear. The variable complex slot of the present invention ncorporates the advantages of the foregoing mechanical; ly variable complex slot and by electrical control of the amplitude and phase of radiation, overcomes the stated disadvantages. Thus, two irises having inductive elements of a ferrite material or a ferroelectric material are disposed in fixed relation with respect to eachy slot in the waveguide and are effectively controlled by an external electrically variable circuit.

It is therefore an object toprovide an electrically variable complex slot. Y

Another object is to provide a variable conductance waveguide slot which is readily altered in-amplitude and phase of radiation. V Y

Still another object is to provide Va variable conductance waveguide slot electrically controllable with respect t amplitude and phase of radiation.

A further object is to provide a fast acting, easily programmed variable complex slot having no moving parts required to provide the variation.

A still further object is to provide a simple multipurpose antenna slot-array electrically controlled for beam type scanning without moving parts.

Other objects and advantages of theinvention will be apparent from the following description considered together with the accompanying drawing, in which:

Fig. 1 is a perspective View, partly in section, of a slotted waveguide in accordance with the invention; and,V

Fig. 2 is a schematic plan view illustrating several typical current distribution patterns occurring during operation.

Referring to Fig. 1 in detail, a section of rectangular waveguide 11 propagates energy from a source (not shown), which may be coupled to input port 12 in any conventional manner. Normally nonradiating centerline slots 13 through a broad Wall of waveguide 11 are spaced apart along the longitudinal centerline. The inclusion of two slots 13 in Fig. 1 is merely illustrative and not in any manner limiting as a single such slot may be used as a variable coupler or as a switch, while a plurality of these slots, in accordance with the invention, is useful as a multipattern antenna array which may be readily adapted for scanning without moving parts. Both of the foregoing aplications will be more fully discussed hereinafter. Thus, since the structure associated with one slot 13 is the same as for the others, the same reference numerals are used for similar elements throughout.

As stated previously, centerline slots 13 are normally nonradiating but may be made to radiate by an asymmetrical disturbance of the current distribution within the waveguide 11. To this end, a rst iris 16 having two substantially thin inductive plates 17 and 18 Vthat are spaced'apart by an impedance matching capacitive plate 19, is mounted transversely in waveguide 11 and dis.- posed `substantially at one end of slot 13. A second similar iris 21 having two inductive plates 22 and 23 and an impedance matching capacitive plate 24 is transversely mounted in waveguide 11 in spaced-apart relation with respect to the first iris 16 at the other end of slot 13. Preferably the distance between the two irises 16 and 21 is less than the length of slot |13.

With the-inductive plates 17, 18 andk 22 23 having equal dimensions and mounted, as described, with such plates against the narrow walls of waveguide 11 and perpendicularly between the broad walls, any disturbance of current distribution of energy propagated through waveguide 11 is still symmetrical. Thus, plates 17, 18 and 22, 23 are preferably made of a ferrite material and individually subjected to static magnetic fields HDC, which may be differentially varied to provide asymmetrical disturbance of current distribution in the area of slot 13. While the plates 17, 18 and 22, 23 have been stated to be made of a ferrite material, such plates may each be formed partially 0f metal and partially of ferrite with either portion disposed to abut the narrow walls of wave- I guide 11.

In accordance with a `preferred embodiment of theV present invention, four electromagnets 26, 27, 28 and 29 are suitably mounted externally of waveguide 11 with pole pieces respectively disposed adjacent ends of inductive plates 17, v18 and 22, 23 at the opposing broad walls of the waveguide 11. The static magnetic lield HDC is indicated by arrows '30 in Fig. 1 in those instances where the magnetic eld structure is omitted for clarity of illustration of other features thereof. Coils 31, 32, V33

, and 34 of electromagnets 26, 27, 28 and 29, respectively, are excited by separate conventional power supplies, represented as batteries 36 in series circuit relation with variable resistors 37.

While horseshoe type electromagnets have been shown and described, Vit will be readily apparent that other congurations may be utilized, as well as solenoidal arrangements, for establishing the required static magnetic elds. Also, permanent magnets having a variable and reversible power supply connected to coils suitably wound thereon may be utilized where Weight is an important factor.

When the electromagnets 26 and 28, for example, apply a greater value of static magnetic field HDC between broad walls of waveguide 11 through the inductive ferrite plate 17 than through plate 18 of one iris 16, an asymmetrical. disturbance occurs in the current distribution which is displaced toward plate 17, and slot 13 radiates. By similarly varying the static magnetic field of each of the inductive Y been described in detail with respect to a particular emplates 17, 18 and 22, 23, there is no radiation from slot l 13 because of Athe zero current value attendant with the symmetrical current distribution pattern 41 in the area of the slot within the waveguide 11.

Now, with the static magnetic field HDC equal to zero through inductive plates 18 and 23 on one side of the waveguide 11 and some value K of. static magnetic field through each of plates 17 and 22 on the other side of the waveguide, the current distribution pattern 42 (see Fig. 2) is displaced toward the inductive plates 17 and 22 so that a component of current is transverse to the slot 13 and the slot radiates in a single phase along the entire length. The single phase radiation results because the current crosses the slot 13 in but one direction. With a change of the static magnetic field HDC so that the magnetic field through plates 17 and 22 is zero and a value K exists through plates 1S and 23, a similar type current distribution pattern 42 exists displaced toward the other side of the waveguide 11. In this latter instance, the slot 13 radiates in substantially the same manner as previously, but with a reversal in phase.

Next consider the current distribution pattern when the static magnetic field through inductive plates 18 and 22 is zero and some value K is established through the plates 17 and 23. Under such condition the current distribution at one end of slot 13 is displaced toward plate 17 and at the other end of the slot in the opposite direction toward plate 23, which results in a transverse component of current in different directions at the respective ends of the slot 13. Thus, the slot 13 radiates with a phase that is a vector addition of the two current components. This latter current distribution pattern is indicated at 43 of Fig. 2. Similarly, with a value K of static magnetic field through plates 18 and 22 and zero static magnetic field through plates 17 and 23, the current distribution pattern, as indicated at 44, is tilted in the opposite direction from that set forth above so that the slot again radiates.

Thus, by varying the differential values of the static magnetic field through the respective plates 17, 18 and 22, 23 of each of irises 16 and 21, the phase of radiation from slot 13 is variable from zero to 360 degrees, as well as in the amplitude of radiation. Should a variation of phase from zero to 18() degrees be satisfactory, two magnets may be utilized with one on either side of the waveguide 11. This may be effectively visualized with respect to Fig. 1 by considering the coils 31 and 33 energized by a single power source 36 and 37 combination and similar energization of coils 32 and 34 by a second similar power source.

Accordingly, the present invention provides a variable complex slot having no moving parts and is particularly useful as a coupler, or as a fast switch, in microwave sysstems. Also, where, as indicated by Fig. 1, a plurality of such slots 13 are suitably spaced along the centerline of a broad wall of the section of rectangular waveguide 11, suitable control of the conductance of the slots results in multipattern or scanning type radiation. Thus a multipurpose antenna array is provided which may be remotely controlled by signals from an electrical programming device, such as a computer, for scanning without the usual type of rotating or moving antenna and associated refiector; that is, the scanning operation is accomplished electrically with a fixed position, slotted section of waveguide.

While the salient features of the present invention have bodiment, it will be readily apparent that numerous moditications may be made within the spirit and scope of the invention, and it is therefore not desired to limit the invention to the exact details shown except insofar as they may be defined in the following claims.

What is claimed is: Y

l. An electrically variable waveguide slot coupler comprising a rectangular waveguide having a resonant slot through a broad wall along the longitudinal centerline thereof, a pair of iris means respectively disposed in said waveguide at either end of said slot and having ferrite inductive elements, and variable means disposed adjacent said elements for establishing differential values of static magnetic field therethrough transverse to the direction of propagation of energy through said waveguide to control amplitude and phase of radiation from said slot.

2. An electrically variable waveguide slot coupler comprising a rectangular waveguide having a resonant slot through a broad wall along the longitudinal centerline thereof, a pair of iris means symmetrically mounted transversely within said waveguide with one at either end of said slot, each of said iris means including ferrite inductive elements, and variable means disposed adjacent said elements for establishing differential values of static magnetic field therethrough transverse to the direction of propagation of energy through said waveguide to control amplitude and phase of radiation from said slot.

3. An electrically variable waveguide slot coupler comprising a rectangular waveguide having a resonant slot through a broad wall along the longitudinal centerline thereof, a pair of iris means symmetrically mounted transversely within said waveguide with one at either end of said slot, each of said iris means including two spacedapart ferrite inductive elements, and at least two variable means respectively mounted adjacent one element of each iris and disposed on opposite sides of said waveguide for establishing differential values of static magnetic field through said elements transverse to the direction of propagation of energy to control amplitude and phase of radiation from said slot.

4. An electrically variable waveguide slot coupler comprising a rectangular waveguide having a resonant slot through a broad wall along the` longitudinal centerline thereof, a pair of iris means symmetrically mounted transversely within said waveguide with one at either end of said slot, each of said iris means having normally symmetrical inductive elements with at least a portion of each element being ferrite, and at least two variable means respectively mounted adjacent one element of each iris and disposed on opposite sides of said waveguide for establishing differential values of static magnetic eld through said elements transverse to the direction of propagation of energy to control amplitude and phase of radiation from said slot.

5t An electrically variable waveguide slot coupler comprising a rectangular waveguide having a resonant slot through a broad wall along the longitudinal centerline thereof, a pair of irises symmetrically mounted transversely within said waveguide in a fixed relation with one vat either end of said slot, each of said irises having two spaced-apart inductive elements with at least a portion of each element being ferrite, and separate variable means mounted adjacent each ferrite portion of said irises for establishing differential values of static magnetic field through said ferrite portions of each iris transverse to the direction of propagation of energy through said waveguide to control amplitude and phase of radiation from said slot.

6. An electrically variable waveguide slot coupler cornprisrng a rectangular waveguide having a resonant slot through a broad wall along the longitudinal centerline thereof, la pair of iris means symmetrically mounted transversely within said waveguide with one at either end of said slot, each of said iris means having two spaced-apart ferrite elements, and rvan'able means disposed adjacent.

each of said elements for establishing differential values of static magnetic field through the two elements of each iris transverse to the direction of propagation of energy through said waveguide to control amplitude and phase of radiation from said slot.

7. An electrically variable waveguide slot coupler comprising a rectangular waveguide having a resonant slot through a broad wall along the longitudinal centerline thereof, a pair of irises having two ferrite side plates spaced apart by an impedance matching capacitive plate, said irises being mounted transversely within said waveguide with one at each end of said slot, and electrically controllable means disposed adjacent each of said side plates for establishing differential values of static magnetic field through such plates of each iris transverse to the direction of propagation of energy through said waveguide to control amplitude and phase of radiation from said slot.

8. An electrically variable waveguide slot coupler comprising a rectangular waveguide having a resonant slot through a broad wall along the longitudinal centerline thereof, a pair of irises having two ferrite side plates spaced apart by an impedance matching capacitive plate, said irises being mounted in fixed relation transversely within said waveguide with one at either end of said slot, and separate electrically controllable means disposed eX- ternally of said waveguide adjacent each of said ferrite side plates for establishing differential Values of static magentic tield through such plates of each iris transverse to the broad walls of said waveguide to control amplitud and phase of radiation from said slot.

9. In a multiphase and -multipattern antenna, the combination comprising a section o-f rectangular waveguide hafving a plurality of spaced-apart resonant slots through a broad wall along the longitudinal centerline thereof, a plurality of irises having ferrite inductive elements mounted transversely within said waveguide with one iris at each end of each of said slots, and separate electrically controllable means disposed adjacent each inductive element of each iris for establishing static magnetic iields therethrough to provide radiation of said slots |variable in phase and amplitude in accordance with particular pat terns of radiation and types of scanning.

References Cited in the le of this patent UNITED STATES PATENTS Miller Aug. 26, 1958 OTHER REFERENCES 

